1. Field of the Invention
This invention relates to high power single spatial mode semiconductor lasers. Accordingly, it is a general object of this invention to provide new and improved semiconductor lasers of such character.
2. Description of the Prior Art
U.S. Pat. No. 4,369,513, issued Jan. 18, 1983 to Umeda et al., discloses a semiconductor laser element having on a predetermined semiconductor substrate a stacked region for optical confinement including an active layer and clad layers, a first electrode disposed on the semiconductor substrate side and a second electrode disposed over the stacked region, and means for constructing an optical resonator, the semiconductor laser element comprising the fact that the means to inject current into the active layer is formed of a plurality of stripe conductive regions which are juxtaposed in traveling direction of a laser beam, and that laser radiations emitted in correspondence with th respective stripe conductive regions form a simply connected net and give rise to nonlinear interactions among them. As a typical example of the current injection means, the conductive regions have a strip-shaped pattern which includes a broader portion and a narrower portion. A coupled-multiple-stripe laser element in which the phases and wavelengths of the laser radiations of the respective strips are uniform is realized. The patent to Umeda et al., however, relates to an array of lasers coupled together; it is specifically concerned with a plurality of stripe conductive regions. In contradistinction, this instant invention relates to a single conductive region and a single laser cavity.
U.S. Pat. No. 4,359,776 for "Device for Generating or Amplifying Coherent Electromagnetic Radiation, and Method of Manufacturing the Device", issued Nov. 16, 1982 to Acket et al., discloses a semiconductor laser/amplifier in which the radiation oscillates only in one longitudinal mode in which, as stated therein, a stripshaped active region exhibits periodic variations in amplification (and preferably also in the amplification profile) in its longitudinal direction over at least a part of its length. The period of the amplification variation is at least ten times the wavelength of the radiation. In general, Acket et al. describes a laser designed to produce a single longitudinal mode (single mode in wavelength) while, in contradistinction, the instant invention is directed to a laser designed to produce a single spatial mode. Acket et al. is directed to producing a spatially periodic amplification variation in the active region. In contradistinction, this instant novel invention, as described more fully hereinafter, does not require a periodic structure. This invention is directed to at least one wide region for providing amplification for high power and at least one narrow region for restricting amplification to a single spatial mode.
U.S. Pat. Nos. 4,11,521 issued Sept. 5, 1978 to Streifer et al. and 4,219,785 to Scifres et al. may be of interest for their showing of a narrow path connected to a separating double path in the active layer. Generally, however, these latter two patents deal with entirely different devices than those heretofore or hereinafter set forth.